110 lines
4.0 KiB
Diff
110 lines
4.0 KiB
Diff
From b160d31ca4e356ff73c2c0259c980dceae8ccc7d Mon Sep 17 00:00:00 2001
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From: Jeremy Drake <cygwin@jdrake.com>
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Date: Wed, 27 Nov 2024 11:22:49 -0800
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Subject: [PATCH 43/N] Cygwin: cache IsWow64Process2 host arch in wincap.
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This was already used in the FAST_CWD check, and could be used in a
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couple other places.
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I found the "emulated"/process value returned from the function largely
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useless, so I did not cache it. It is useless because, as the docs say,
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it is set to IMAGE_FILE_MACHINE_UNKNOWN (0) if the process is not
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running under WOW64, but Microsoft also doesn't consider x64-on-ARM64 to
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be WOW64, so it is set to 0 regardless if the process is ARM64 or x64.
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You can tell the difference via
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GetProcessInformation(ProcessMachineTypeInfo), but for the current
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process even that's overkill: what we really want to know is the
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IMAGE_FILE_MACHINE_* constant for the Cygwin dll itself, which is
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conveniently located in memory already, so cache that in wincap also for
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easy comparisons.
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Signed-off-by: Jeremy Drake <cygwin@jdrake.com>
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(cherry picked from commit 46f7bcc1e575826f6d3e4a5770ae61423d9be5a9)
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---
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winsup/cygwin/local_includes/wincap.h | 4 ++++
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winsup/cygwin/path.cc | 6 ++----
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winsup/cygwin/wincap.cc | 19 +++++++++++++++++++
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3 files changed, 25 insertions(+), 4 deletions(-)
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diff --git a/winsup/cygwin/local_includes/wincap.h b/winsup/cygwin/local_includes/wincap.h
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index c148727..250866f 100644
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--- a/winsup/cygwin/local_includes/wincap.h
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+++ b/winsup/cygwin/local_includes/wincap.h
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@@ -42,6 +42,8 @@ class wincapc
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RTL_OSVERSIONINFOEXW version;
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char osnam[40];
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const void *caps;
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+ USHORT host_mach;
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+ USHORT cygwin_mach;
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bool _is_server;
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public:
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@@ -61,6 +63,8 @@ public:
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{ return (size_t) system_info.dwAllocationGranularity; }
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const char *osname () const { return osnam; }
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const DWORD build_number () const { return version.dwBuildNumber; }
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+ const USHORT host_machine () const { return host_mach; }
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+ const USHORT cygwin_machine () const { return cygwin_mach; }
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#define IMPLEMENT(cap) cap() const { return ((wincaps *) this->caps)->cap; }
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diff --git a/winsup/cygwin/path.cc b/winsup/cygwin/path.cc
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index 89aa931..661a688 100644
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--- a/winsup/cygwin/path.cc
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+++ b/winsup/cygwin/path.cc
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@@ -4825,14 +4825,12 @@ find_fast_cwd_pointer ()
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static fcwd_access_t **
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find_fast_cwd ()
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{
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- USHORT emulated, hosted;
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fcwd_access_t **f_cwd_ptr;
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- /* First check if we're running in WOW64 on ARM64 emulating AMD64. Skip
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+ /* First check if we're running on an ARM64 system. Skip
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fetching FAST_CWD pointer as long as there's no solution for finding
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it on that system. */
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- if (IsWow64Process2 (GetCurrentProcess (), &emulated, &hosted)
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- && hosted == IMAGE_FILE_MACHINE_ARM64)
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+ if (wincap.host_machine () == IMAGE_FILE_MACHINE_ARM64)
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return NULL;
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/* Fetch the pointer but don't set the global fast_cwd_ptr yet. First
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diff --git a/winsup/cygwin/wincap.cc b/winsup/cygwin/wincap.cc
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index 30d9c14..deecf8b 100644
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--- a/winsup/cygwin/wincap.cc
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+++ b/winsup/cygwin/wincap.cc
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@@ -235,9 +235,15 @@ static const wincaps wincap_11 = {
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wincapc wincap __attribute__((section (".cygwin_dll_common"), shared));
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+extern IMAGE_DOS_HEADER
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+__image_base__;
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+
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void
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wincapc::init ()
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{
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+ PIMAGE_NT_HEADERS ntheader;
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+ USHORT emul_mach;
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+
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if (caps)
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return; // already initialized
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@@ -282,4 +288,17 @@ wincapc::init ()
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__small_sprintf (osnam, "NT-%d.%d", version.dwMajorVersion,
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version.dwMinorVersion);
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+
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+ if (!IsWow64Process2 (GetCurrentProcess (), &emul_mach, &host_mach))
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+ {
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+ /* If IsWow64Process2 succeeded, it filled in host_mach. Assume the only
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+ way it fails for the current process is that we're running on an OS
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+ version where it's not implemented yet. As such, the only realistic
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+ option for host_mach is AMD64 */
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+ host_mach = IMAGE_FILE_MACHINE_AMD64;
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+ }
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+
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+ ntheader = (PIMAGE_NT_HEADERS)((LPBYTE) &__image_base__
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+ + __image_base__.e_lfanew);
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+ cygwin_mach = ntheader->FileHeader.Machine;
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}
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